| Leptomeryx(noun, creature, appearance, eocene) |
| Limnocyon(noun, creature, appearance, eocene) |
| Litopterna(noun, creature, appearance, paleocene) |
| Lobocarcinus(noun, creature, appearance, eocene) |
| Macginitiea(noun, creature, appearance, eocene) |
| Machaeroides(noun, creature, appearance, eocene) |
| Macraucheniidae(noun, creature, appearance, eocene) |
| Mammacyon(noun, creature, appearance, oligocene) |
| Merycochoerus(noun, creature, appearance, oligocene) |
| Merycoidodontoidea(noun, creature, appearance, eocene) |
| Mesonychid(noun, creature, appearance, paleocene) |
| Mesonychidae(noun, creature, appearance, paleocene) |
| Mesonyx(noun, creature, appearance, eocene) |
| Mesotheriidae(noun, creature, appearance, eocene) |
| Miacidae(noun, creature, appearance, paleocene) |
| Miohippus(noun, creature, appearance, eocene) |
| Miotylopus(noun, creature, appearance, oligocene) |
| Mixodectidae(noun, creature, appearance, paleocene) |
| Nanotragulus(noun, creature, appearance, eocene) |
| Neocynodesmus(noun, creature, appearance, oligocene) |